VM 125 Disk on NAS Failing with I/O Errors — Migration and Backup Fail

powersupport

Well-Known Member
Jan 18, 2020
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Hello,


I have a VM (ID 125) running WHM/cPanel. When creating it, I accidentally placed the disk on my NAS Backup storage instead of local storage (local_btrfs).


Symptoms / Issues:
  • The VM sometimes shuts down automatically after starting.
  • Inside the VM, dmesg shows repeated I/O errors on /dev/sda.
  • Attempts to move the disk to local storage via GUI (Disk → Move Storage) fail consistently around 21 GB:


qemu-img: error while reading at byte 21696741376: Input/output error

  • Backups via PBS also fail with Input/output error (job stops at ~20 GB).


Logs / Info:
  • Proxmox logs show VM 125 starts normally, no host-side shutdowns.
  • NAS disk path: NAS-BACKUP:125/vm-125-disk-0.qcow2
  • VM disk size: 1 TB
  • Old backups exist but are too outdated to restore. (can't use the backup)


Questions:
  1. What is the safest way to recover or move this VM disk to local storage without losing data?
  2. Are there any recommended steps to prevent VM crashes while trying recovery?

Any advice is highly appreciated.